mchero

Hello All!

Hello all, Robert McHenry here. My 1st post in this forum!

Last November I purchased a 36' 1993 Pace Arrow Diesel pusher with a Cummin 8.3l 250HP turbo diesel. 170K miles on her & shortly after purchase I noticed a ticking sound while running. I discovered that what I thought was a simple #6 exhaust port gasket leak turned out to be a cracked flange! To make a long story short, I purchased a Cummins refurbished head & swapped out the head myself. at 170K I could still see the cross hatch patterns (from hone) on the cylinder walls! I love this diesel!

All went well. I took a 7K mile RT from Concord NH. to Ventura CA. and back. Coach ran like a top & averaged about 8 to 10 MPG. I did experience some overheating when I was in Las Vegas. It was about 110 deg. out. I simply slowed down & the temp dropped back down to normal.

I have some questions about my Cummins that I hope you folks can answer.

First, the overheating issue. The cooling system is in great shape. Thermostats present. I have a rather large hydraulic driven fan behind the side mount radiator that moves a TON of air! I believe I should remove the CAC (Charge Air Cooler) and give her a good cleaning! While in CA. I sprayed some Simple Green in the radiator & saw lots of dirt & gunge when I rinsed. Am I on the right track here?

Performance.
The Cummins does not blow any smoke when I put her under a load. I don't have any gauges, e.g. boost or Pyro. so I have NO clue as to what the turbo is doing. I checked the waste gate & it appears functional. It has a small copper line that runs down to the intake manifold and also branches off to the pump. I assume the line to the pump feeds a diaphram that will back off the fuel rate if the boost pressure goes too high.

I have seen a few posts where some people have stated that their fuel pressure spring was weak and after replacing with a new spring a noticeable performance boost was seen. Where is this spring? is it easy to remove, test, replace? Do I need a part number?

Fuel plates, I have seen that replacing the fuel plate would gain power BUT I want to stay stock since I don't have a boost or Pyro. guage.

Can I connect a simple boost gauge to the Cummings to determine if I have proper boost? What should I expect to see?

I think I'll hold off with the questions for now. Thanks for listening & I expect I will get a lot of great information off of this forum!

Thanks!

Robert
Concord, NH

mr T

maybe check ur thermostat first and replace that with a new unit...ur in las vegas! its a desert! u gotta watch diesels in extremely hot weather and ease up on the throttle...make sure u have anough coolant in there too....everything else sounds normal to me

....unless u did a bad job on the head

wannadiesel

Welcome!

If the radiator is original 1993 issue, I think it ought to be removed and boiled out. The engine should be flushed thoroughly as well. The CAC does not affect coolant temp much.

You are correct on the purpose of the plumbing between the manifold and the pump.

Don't mess with the fuel plate until/unless you get a pyrometer.

The spring would be in the lift pump, located about halfway back, down low on the pump side of the engine. If you give a Cummins dealer your ESN and CPL# they can get you a new spring. Get the whole lift pump rebuild kit so you have all the seals and gaskets needed. All that said, I doubt you will see much difference. With only 250 HP this thing will never be a rocket ship. If it'll do the speed limit pushing a 20 MPH head wind on flat ground, it's doing fine.

You can hook up a boost gauge, get a 30 or 35 psi gauge. I would expect to see 15-20 psi with the engine working hard.

mchero

Mr T Thanks for the tips. Will look at boiling out the radiator is a good idea. I watch the coolant carefully and make sure I have the correct ammount of additive in the coolant.

wannadiesel, Thanks for the information! That spring is locted in the lift pump? I thought it would be in the injector pump. I'll look into rebuilding the lift pump. I will also get a boost guage & take her out for a drive and see where I'm at.

Never have and never will expect the 8.3l to be a rocket ship. I'm not looking to do 75 over those 6% grades. Don't even plan on uprating. I just want all specs to be correct.

That statement about the CAC above, The rear mount radiator in the diesel pushers are known to pick up oil from the crankcase breather and then start collecting dirt thus restricting cooling. The side mount radiator does not have that problem but I think that a good inspection followed by a good cleaning will not hurt.

That fan moves a ton of air. I could start a side job blowing leaves off the streets for the city of Concord!